**Core Concept**
Beta blockers are the preferred first-line treatment for managing hypertension in patients with angina due to their ability to reduce myocardial oxygen demand by decreasing heart rate and contractility. This is essential in stabilizing angina pectoris by reducing the frequency and severity of angina attacks.

**Why the Correct Answer is Right**
The mechanism of beta blockers in managing hypertension in patients with angina involves their action on beta-1 receptors in the heart, which leads to a decrease in cardiac output and a subsequent decrease in myocardial oxygen demand. This is achieved through a reduction in heart rate (negative chronotropic effect) and a decrease in the force of cardiac contractions (negative inotropic effect). By reducing myocardial oxygen demand, beta blockers help in stabilizing angina pectoris and improving the quality of life for patients with angina.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because ACE inhibitors, while beneficial in patients with heart failure and those with diabetes, are not the first-line choice for managing hypertension in patients with angina.
* **Option B:** This option is incorrect because calcium channel blockers can be used in patients with angina, but they are not the preferred first-line treatment due to their potential to increase myocardial oxygen demand in certain circumstances.
* **Option D:** This option is incorrect because diuretics are not the preferred first-line treatment for managing hypertension in patients with angina due to their potential to worsen angina by increasing myocardial oxygen demand.

**Clinical Pearl / High-Yield Fact**
Beta blockers are the preferred first-line treatment for managing hypertension in patients with angina due to their ability to reduce myocardial oxygen demand, which helps in stabilizing angina pectoris and improving the quality of life for patients with angina.

**Correct Answer: C.